In a rotor of a rotary electric machine, the heat generation amount of the rotor is increased and the temperature is increased when the output is increased, as a result, an insulation failure occurs. Accordingly, the increase of temperature is prevented by efficiently cooling conductors forming respective turns of a rotor winding to thereby allowing electric current to flow in the rotor winding as much as possible in order to obtain a higher output. That is, a ventilation hole for cooling penetrating respective conductors of the rotor winding in a stacked direction is provided, and a cooling gas such as air or hydrogen is allowed to flow in the ventilation hole directly for cooling the rotor winding (for example, Patent Document 1). Furthermore, in order to increase cooling efficiency by the cooling gas, rib-shaped projections parallel to an axial direction of the rotor are provided on a wall surface of the ventilation hole for the cooling gas and allowing the cooling gas flowing in a radial direction to be a turbulent flow state from a laminar flow state near the wall surface, thereby improving heat radiation performance in an inner wall of the ventilation hole for cooling (for example, Patent Document 2).